When you ally with the defensive main player, and your side win, each ally receives "rewards" (one for each ship involved in the encounter).
Rewards consist of any combination of cards from the deck or ships from the warp (returned to colonies)- and, with the release of Cosmic Incursion, allies can take rewards from a separate deck called the Reward Deck.
The Reward Deck includes many cards that are not available in the normal encounter deck:
-Kickers (available in some previous editions of CE, but not FFG's until now)
-Crooked Deals (a special kind of negotiate card)
-Negative Attack cards
There are also some duplicates of cards that are available in the normal encounter deck, like Cosmic Zap.
Some of the new aliens in Cosmic Incursion take advantage of the Reward Deck, like Ghoul and Mercenary.
But one of the most interesting and subtle changes to Cosmic Encounter by the inclusion of the Reward Deck is the dynamics of defensive alliance.
Over many years, the trend I have seen in alliance is that players ally more frequently with the offense, especially early in the game. Everyone starts the game with a full hand of cards, at least some of which are pretty good, and no ships in the warp. There isn't as much need for rewards. Gaining a colony, without must risk or effort as an offensive ally is more attractive.
The Reward Deck has changed that, at least in a small way. Players have more incentive to collect rewards in general. However, defensive main players have also been forced to take rewards into consideration more carefully when they invite. The odds of drawing really useful cards as rewards from the encounter deck is even at best (and in reality, you are probably more likely to get something no better than what you're already holding). There's a better chance of getting good cards from the Reward Deck at any given time.
This also makes the end of the game speed up as well. In the past, when one player tries to go for the win, he or she can pretty much count on having to face all of the other players are full strength. If you don't beat them, they will be collecting some pretty good cards for rewards if they get them from the Reward Deck. This means they have a much better chance of getting that solo win on their turn.
I love this dynamic quite a bit.
The other great thing about the Reward Deck is the ability to add in new cards to the game without greatly affecting the card distribution in the encounter deck. The Rifts, Kickers, etc. that are part of the CI Reward Deck are a great addition, but it would be too much to have shuffled into the normal encounter deck (definitely too much to teach to a brand new player). The Reward Deck can grow at a faster rate than the encounter deck as well- since its distribution is a little bit easier to manage.
Of course, Flares are the great equalizer in the card category. You can't get them in the Reward Deck, so if that's what you're after, you should stick to taking your rewards from the main encounter deck. As for ships, you can always hope for a Rift card, and increase the number of ships you are able to free- or play it safe and just take rewards from the warp.
The biggest "controversy" with the new Reward Deck is the back art. Originally, the cards in the Reward Deck were designed to match the normal encounter deck so you could never tell which cards were which. FFG has chosen to make the art different, letting everyone know how many Reward cards you have and when you're playing one. It's an interesting move, and the presence of the Rift cards mitigates them as targets for compensation (but probably only a little). Rift cards can be used to free ships from the warp like a Warp Break artifact (which doesn't actually exist yet in the FFG edition), or, when they are taken from your hand by another player, they cause the loss of ships to the warp by the playing taking the Rift- a sort of boobytrapped card.
I like the Rifts a lot, but I can still go either way on whether having different back art is the way to go. In my custom CE sets, I still have the Reward Deck cards matching the encounter deck cards. If you've played with the Reward Deck, what's your impression? Have you noticed more or fewer defensive allies? Different card art yea or nay?